1. Field of the Invention
The present invention relates to a shearwall for opposing lateral forces on building walls, and in particular to a prefabricated shearwall including a central diaphragm having a corrugated or non-planar cross section to improve the ability of the shearwall to withstand lateral forces such as those generated in earthquakes, high winds, floods and snow loads.
2. Description of the Related Art
Shearwalls were developed to counteract the potentially devastating effects of natural phenomena such as seismic activity, high winds, floods and snow loads on the structural integrity of light-framed constructions. Prior to shearwalls and lateral bracing systems, lateral forces generated during these natural phenomena often caused the top portion of a wall to move laterally with respect to the bottom portion of the wall, which movement could result in structural failure of the wall and, in some instances, collapse of the building. Shearwalls within wall sections of light-framed constructions provide lateral stability and allow the lateral forces in the wall sections to be transmitted through the shearwalls between the upper portions of the wall and the floor diaphragm or foundation of the building where they are dissipated without structural effect on the wall or building.
In constructions such as residences and small buildings, a lateral bracing system typically includes vertical studs spaced from each other and affixed to horizontal top and bottom plates. The bottom plate is typically anchored to the floor diaphragm or foundation. The bracing system typically further includes sheathing affixed to the studs, upper plate and/or lower plate to increase structural response to lateral forces. The sheathing used is generally oriented strand board (OSB) or plywood, but fiberboard, particleboard and drywall (gypsum board) are also used. Alternatively or additionally, light-frame construction wall sections may include prefabricated shearwall sections, which can be positioned between the vertical studs and affixed to the studs and the top and bottom connecting plates. The sheathing or prefabricated panels can also be placed adjacent door and window frames to improve the response to lateral forces at these locations.
A conventional prefabricated shearwall 20 is shown in the perspective and cross-sectional views in FIGS. 1 and 2. The shearwall includes an interior diaphragm 22 formed of thin gauge sheet steel which is affixed to an exterior wooden frame (not shown). The diaphragm is conventionally planar with the edges along the length of the diaphragm being formed to respective lips 26 and 28. The lips 26, 28 allow the diaphragm to be affixed to the wooden frame.
While a prefabricated shearwall of the construction shown in FIGS. 1 and 2 provides lateral force response and resistance, it has limitations with respect to its lateral load bearing capabilities. There is, therefore, a need for an improved shearwall capable of withstanding greater lateral loads.